import java.util.*;
/*
public class ListNode {
    int val;
    ListNode next = null;

    ListNode(int val) {
        this.val = val;
    }
}*/
public class Solution9 {
    public ListNode FindFirstCommonNode(ListNode pHead1, ListNode pHead2) {
        ListNode p1 = pHead1;
        ListNode p2 = pHead2;
        while(p1 != null && p2 != null){
            if(p1 == p2){
                return p1;
            }
            p1 = p1.next;
            p2 = p2.next;
            if(p1 == null){
                p1 = pHead2;
                pHead2 = null;
            }
            if(p2 == null){
                p2 = pHead1;
                pHead1 = null;
            }
        }
        return null;
    }
}
